In a universal mobile telecommunications system (UMTS), a radio link from a user equipment (UE) to a core network (CN) is set up by using a radio bearer (RB) set up between an access node and a radio network controller (RNC) and a radio access bearer (Radio Access Bearer, RAB) set up between the RNC and the CN, thereby implementing circuit switched domain services of the UE.
After the radio link from the UE to the CN over the RNC is established, the RNC relocates the UE active in a circuit switched domain service to another RNC according to the power load status of the access network and/or the core network. The source RNC and the target RNC may support different voice coding schemes and the coding scheme configured for the UE is the same as the coding scheme supported by the source RNC. Therefore, when the voice coding scheme supported by the target RNC is different from that supported by the source RNC, the coding scheme of the UE and the coding scheme of the target RNC need be unified in the process of relocating the UE from the source RNC to the target RNC. This keeps a consistent coding scheme between the UE and the target RNC.
In a prior art, during the relocation of a UE between RNCs, the source RNC notifies the target RNC of the coding scheme configured for the UE and the source RNC through the CN, the CN selects a coding scheme supported by both the UE and the target RNC as the coding scheme used for RB setup between the UE and the target RNC according to the coding scheme configured for the UE and the coding scheme supported by the target RNC. In a UE-involved RNC relocation process (UE Involved in Relocation of SRNS), if the coding scheme indicated by the CN for the target RNC is inconsistent with the coding scheme used by the UE and the source RNC, the target RNC reconfigures the coding scheme for the UE to a coding scheme consistent with the coding scheme indicated by the CN for the target RNC before performing RNC relocation of the UE. In a UE-not-involved RNC relocation process (UE not Involved in Relocation of SRNS), if the coding scheme indicated by the CN for the target RNC is inconsistent with the coding scheme used by the UE and the source RNC, the target RNC rejects the relocation of the UE directly.
During the implementation of the relocation of a UE between RNCs with different coding schemes, the inventor discovers that the prior art has at least the following problem: when the radio link carrying the circuit switched domain services of the UE is controlled by the target RNC, only the UE-not-involved RNC relocation process (UE not Involved in Relocation of SRNS) can be implemented, in which case, if the coding scheme configured for the UE and the coding scheme indicated by the CN for the target RNC are inconsistent, the UE cannot be relocated to the target RNC.